Asphalt pavement.



UNITE STATES- Patented September 15, 1903.

PATENT OFFICE.

' ASPHALT PAVEM ENT.

SPECIFICATION forming part of Letters Patent No. 738,965, dated September 15, 1903.

Application filed January 9, 1901. Serial No. 421627. (No specimena) A TOLLZZ whom it may concern.-

Be it known that I, FREDERICK J. WARREN, a citizen of the United States, and a resident of Newton, in the county of Middlesex and State of Massachusetts, have invented a new and useful Improvement in Asphalt Pavements, of which the following is a full, clear, and exact description.

My invention has for its object an improvement in the method of laying asphalt pavements and in the completed pavement. These improvements I practice by means of an agent which enables the hard asphalt and its permanent flux-to be combined at a lower temperature than is now usually practical, and which permits the cement so made to be used and worked at the time of the making of the paving composition at a lower temperature than is now prudent, and which produces the same results if the hard asphalt and flux are combined at the time the paving composition is made and used, and which also allows the pavement to be laid at a lower temperature and under less favorable conditions of the atmosphere than are now necessary and are more sure of producing a perfect pavement because of the superior conditions under which it is made and laid. My improvement also is advantageous in that it reduces the cost of making the cement and the paving composition and of laying the pavement. This comes from the saving in fuel which it occasions, from the use of less complicated and expensive machinery, arising from the fact that the cement and composition are handled at lower temperatures, from the saving obtained from the use'of less skilled help in the manufacture of the composition and in the laying of the pavement, and from the obtainment of more uniformly satisfactory results.

To practice my invention, there is combined with the hard asphalt and its permanent flux an agent which I term a temporary liquefier and fixer, and the purpose of which is to very much reduce the high temperature at which the asphalt and its permanent flux may be combined in the manufacture of cements and in the manufacture and laying of pavements. This temporary liquefier and fixer must have these properties: First, it must readily combine with the asphalt, permanent flux, and such other paving ingredients as are used; second, it must materially reduce the temperature at which the asphalt, permanent flux, and other ingredients for form= ing the pavement are combined; third, it must possess high volatility and to a very considerable extent become dissipated without injuring the asphalt or its flux or any of their properties combined or uncombined with other paving ingredients, in order that after serving its purpose as a temporary liquefier it may then serve as a quick fixer for permitting the rapid stiffening or hardening of the laid pavement and without taking from the laid pavement any of the qualities imparted to it by the asphalt and permanent flux, but rather giving to the finished pavement a desirable quality or condition which it doesnot now possess in that it provides a longer interval of time in which the pavement may be reduced to its permanent or final state, and thus enables its solidification to be continued for a longer period than is now possible.

Any temporary liquefier or fixer which possesses the above qualities may be employed andat anytime. I would mention among the desirable temporary liquefiers and fixers the various light oils having a low evaporation pointjs'uch as n fihtha, benzene, and similar coal-tar light oils or other rapid-drying oils.

The proportion of the temporary liquefier and fixer to the asphalt-cement depends upon the temperature at which it is united with it and also upon the degree of hardness of the pavement which it is desired to obtain and the time in which it is necessary to obtain such hardness after the pavement has been laid. The ordinary limits of this proportion must therefore necessarily vary considerably. Ordinarily a proportion of five to fifteen per cent. in weight, of the temporary liquefier and fixer as compared with the amount in weight of the pure bitumen employed in the cement -would serve the purposes of my invention; *but I would not be understood as confining myself to this proportion of the temporary liquefier and fixer, as for some purposes a somewhat-lower percentage may be used and for other purposes a higher percentage. I would here state that the larger the proportion of the temporary liquefier and fixer to the amount of bitumen in the cement the greater its fluidity at a low melting-point, and

where it is desired to employ a mixture that shall flow readily at atmospheric temperatures quite a large additional percentage of the temporary liquefier and fixer must be used.

The percentage of the permanent flux use in my improved compositions is preferably that which is now ordinarily used for obtaining the standard asphalt-cements of the market which are used for the same purpose. This proportion is generally from eight to twenty-two pounds of a permanent flux of standard petroleum residuum to one hundred pounds of asphalt of the standard of the Trinidad Lake refined brand.

The kind and size of the earthy, stony, or mineral ingredients with which the asphalt and temporary liquefier and fixer are used in forming a paving or other mixture varies according to the place where used and the effeet which it is desired to obtain. They may be in the nature of a fine powder or of a coarser powder or larger grains and often of pieces of a size varying from three inches in diameter downward, or they may consist of any desired combination of these ingredients. Ordinarily the proportion which these ingredients bear to the prepared cement or composition will be from eighty to ninety per cent., according to the cement employed, locality, laying of the mixture, its use, and other conditions.

The asphalt-cement may constitute a portion of any part of the pavement, either the subbase, base, intermediate layers or surfacing, or may enter into the composition of all.

By pavement I mean any artificial surfacing in the nature of a roadway, gutter, sidewalk, floor, or similar surfacing. I would further add that my improved asphalt-cement alone or myimproved mastic may be used to form a thin surfacing to a macadam, Telford, or any other new or old pavement or to improving or renewing the surfacing of worn or old pavement of any kind, and I would not be understood as indicating by these uses that I confine the employment of the invention to any type, form, or use of pavement, as it has a much broader range of use than have the old asphalt cements, mastics, and pavements.

In use when the cement, mastic, or paving composition is spread in relatively thin layers,as in a pavement or surfacing, by which large areas become exposed to the air, and therefore to influences favorable to rapid evaporation of the temporary liquefier, the ocment, mastic, or composition will stiffen and harden and become fixed with a quickness or rapidity which depends upon the amount of the temporary liquefier and fixer used in the cement, mastic, or composition.

In the manufacture of the cement, mastic, or composition a low or moderate degree of heat may be employed, or it may be manufactured at atmospheric temperature, according to the use: to which it is to be put or the degree of fluidity which it should have at atmospheric temperature.

On account of the softness or fluidity of my improved cement and because the time in which it hardens is longer it may be more intimately mixed with the ingredients of the mastics and of the paving compositions than where such incorporation takes place under a high temperature, and there is therefore imparted to the mastic and paving compositions greater adhesiveness and power to permanently combine the earthy and mineral particles together and permit them to be compacted into a denser structure than would otherwise be possible, and these results provide the pavement with greater strength and greater wearing properties than are possessed by the old types of asphalt pavements.

It should be understood that the main purpose of this invention is to provide means whereby the asphalt may be associated with other ingredients in themanufacture of a paving or other mixture, and by which the said 'mixtnre may be laid or applied, and also by which the laid or applied mixture may be suitably set under conditions which are favorable to the working of the asphalt in this manner at atmospheric or relatively low temperatures, and in order that all the advantages which naturally come from such a condition of Working may be obtained and that to this end the inventor uses a temporary liquefier and fixer in steps in the process of making and laying pavements where always before it has been considered undesirable to use ent of the United States 1. The method of laying a pavement at temperatures as low as atmospherical, consisting in treating the asphalt cement or binder as commonly provided with permanent heavy fluxing-oils, with a temporary solvent of light oils, applying the resulting fluid to the mineral or wearing ingredients, and pressing the whole into place.

2. The method of laying pavements consisting in treating any asphalt cement or hinder provided with heavy permanent fluxing-oils with a temporary light solvent fluxing it at temperatures as low as atmospherical, applying the resultingfluid to the mineralor wearing ingredients and pressing the mixture into place without the application of external heat.

3. The method of laying a pavement at temperatures ranging from 200 down, consisting ing the mixture Without the application of eX- ternal heat.

5. Apavement composed of mineral or wearing ingredients in combination with asphalt and permanent softening-oils, and. a flux of light temporary oils.

6. Apavementcomposedofmineralorwean ing ingredients in combination with asphalt provided With heavy permanent fluxing-oils and a solvent of light oils, fluxing the same at low temperatures.

7. A pavement structure having a Wearingsurface composed of mineral and wearing ingredients, and an asphalt cement or binder provided Withheavy permanent fiuXing-oils and a temporary light solvent, fluxing and maintaining soft the lower stratum of said surfacing after the upper stratum has become hard.

8. Apavement composed of mineral orwearing ingredients in combination with a cement or binder of asphalt provided With heavy permanent fiuXing-oils, fluxed by temporary mineral oils.

9. The method of making and using asphalt cements or compositions consisting in combining asphalt, a permanent combining-flux, a volatile temporary liquefier and fixer and a mineral base and laying said composition While the volatile liquefier is resident in it and allowing said composition to set by the evaporation of the liquefier.

FREDERICK J. VVARREN'.

Witnesses:

F. F. RAYMOND, 2d, J. M. DOLAN. 

